Reversible radial-flow turbine.



F. LJUNGSTRUM.

REVERSIBLE RADIAL FLOW TURBINE.

APPLICATION FILED NOV. 14. I917.

1 ,273,633. Patented July 23, 1918.

Inventor: FY-echik Hun gstrb'm His Jitter-neg.

NrrE snares PATEN orrioE.

FREDRIK LJ'UNGSTIRbM, F STOGKHOLM, SWEDEN, ASSIGNOR TO AKTIEBOLAGET LJ'UNGSTROM ANGTURBIN, A CORPORATION OF SWEDEN;

I REVERSIBLE RADIAL-FLOW TURBINE.

Specification of Letters Patent.

Patented July 23, 1918.

Application filed November 14, 1917. Serial N 0. 202,042.

Toall whom it may concern:

Be it known that I, F REDRIK LJUNosTnoM, a subject of the King of Sweden, residing at Stockholm, Sweden, have invented certain new and useful Improvements in Reversible Radial-Flow Turbines, of which the following is a specification.

The present invention relates to radial flow turbines having rotors that revolve in opposite directions, and has for its object to modify them in such manner as to render them reversible.

It is common practice at the present time to reverse axial flow turbines, and their construction is such that no practical difficulties are experienced. To accomplish this a separate reversing element is mounted on the same shaft as the forward driving element, and usually on the exhaust end, said elements being contained in the sam e casing. In such a case both elements are of the same general construction, the blades on one element, however being reversed with respect to those on the other. Each element has, of course, suitable means for supplying motive fiuid thereto. A construction of this kind obviously increases the axial length of the turbine. It has also been proposed to place reversing blades outside of the forward driving blades of such a turbine, but this has been abandoned for various reasons in favor of the one above described.

In radial flow turbines of the character referred to the use of two additional sets of reversing blade elements of the same general construction as the two forward driving elements would increase the overall length of the turbine and lead to an unsatisfactory mechanical construction, and also to a loss of economy. This is primarily due to the difficulty of supplying motive fluid to the reversing elements and transmitting the power developed thereby to the shafts. According to the present invention the difliculties are, overcome by constructing the reversing elements to operate on the axial flow two rotors or elements, which is preferable from a constructional standpoint, the blades should be located at a relatively great radial dlstance from the axis to provide the high blade speed required. This general arrange ment has the advantage that sufficient space is provided for the inner blading used for forward driving, with the result of effectively utilizing the motive fluid under such conditions. The blade elements employed for forward driving may operate wholly on the radial flow principle, or a part of the blading may operate on the radial flow principle, and the remainder on the axial flow principle. The latter arrangement is preferable because of the difliculties of constructing rings of large diameter having axially extending blades of considerable length, and also because of the possibility of mounting the reversing blades directly on and outside of the axial flow blades of the forward driving elements. In this manner the enlarged diameter desired for the reversing blades is readily obtained.

For a consideration of what I believe to be novel and my invention, attention is directed to the accompanying description and claims appended thereto.

In the drawing is illustrated a turbine of my improved construction, wherein Figure 1 is an axial section of a. turbine of the combined radial and axial flow type; Fig. 2 is a modification of the reversing portion of theturbine which is velocity compounded; Fig. 3 is a further modification wherein the steam acts by pressure steps or stages on the reversing blades of the two separate rotors, said steps or stages being arranged in series, and Fig. 4 is a furtlier modification permitting of separate control of the two rotors.

4 indicates the turbine casing which is divided in an axial plane in the usual manner. Located in the casing are two elements of rotors 5 and 6, each having a shaft 7, said elements being provided with concentric rows of axially .extending high pressure blades 8 that cause the elements to rotate in opposite directions. Surrounding the high pressure blades and mounted on the rotors are rings of intermediate pressure blades 9 which are provided with reinforcing rings 10. Also mounted on the rotors are radially extending low pressure blades 11 that re ceive steam from the intermediate pressure blades and through which the steam flows axially into the exhaust chamber 12. The blades 11 cooperate with the radial flow blades toroduce rotation of the blade eleinents an their shafts in opposite direc-- tions. The steam is caused to flow right and left to these blades by the annular deflector 13 which has two curved faces 14:.

The deflector is supported by yielding mem-' bers 15 so that it is free to expand and contract independently of the outer casing 4. On op osite sides of the curved walls of the deflector and carried by the deflector are static .iary blades, nozzles or fluid directing devices 16 which direct the steam from the intermediate blades in its passage to the op- .positely revolving low pressure blades 11.]

Since these latter rotate in opposite directions the working faces must be reversed with respect to each other, and for the same reason the fluid directing devices 16 are reversely disposed.

Surrounding the deflector is a cylindrical wall 17 which cooperates with it to form a steam chest or chamber 18 to which high pressure steam for reversing is admitted bythe conduit 19. On opposite sides of the chamber are blades, nozzles or fluid directing devices 20 which are so disposed as to discharge steam in opposite directions. Situated adjacent these devices are radially disposed reversing blades 21 that are supported by the forward drivin blades 11. They may be'integral withsaid blades or attached directly thereto or to the rings 22 their speed for a given shaftspeed will be ,high which is necessary to give good economy of operation- Furthermore, when the turbine parts" are rotating in their normal manner the losses due to windage will be so small that they can be disregarded because they are rotating in an atmosphere of low pressure steam; i. e., a pressure which closely approximates that of the condenser (not shown) which is connected to the'exhaust conduit 25. It will also be seen that the flowof exhaust steam from the reversing blades is direct to the condenser, there being no long or complex passages for it to flow through. This assists in improving the economy of the reversing operation. It'is important to support the steam-. chest or chamber 18 by yielding or elastic means, such as the parts 15 for example within .the turbine casing, because when the turbine parts are rotating forwardly, as is normally Othe'case, the walls of the chest are relachanged because it is still subjected to the temperature of exhaust steam only. I have shown one type of means for supporting the chest, but the invention is not specifically limited thereto since other means will a readily suggest themselves to those skilledin the turbine art.

On opposite sides of the rotors and mounted within the casing are high pressure steam chests 30 and 31. Each of these is provided with an annular groove 31 so as to forma relatively thin wall 32 to permit the chest to expand and contract" independently of the turbine casing to the desired extent. Steam or other elastic fluid is admitted to the chests by the conduits 33.

-In each' chest is a bearing for the rotor shaft. 1 Between the inner faces of the chests and the rotors are labyrinth or equivalent packing devices 34 to prevent the free escape of steam from the chest to the condenser, said means also forming a balancing device to absorb thrust due to the ac tion of the steam in flowing through the working passage formed by the rows of blades. The steam from the chambers 35 in, the chests flows through the annular port 36 and thence through the passages 37, of which there are a large number, to the inner part of the blade system from which it flows radially outward to the deflector and thence axially'through the radiallydisposed blade system to the exhaust.

For reversing the conduits 33 are shut off and conduit 19 opened to high pressure. This causes the rotors to revolve in the opposite sense from which they rotated before, due to the action of the reversing blade system.

I Fig. 2 of the drawing shows a modifica- I tion of the invention for use where a lower reversing speed is desired or where the pitch diameter of the reversing blades is such that the blade speed is not sufliciently high to extract the desired amount of energy from the steam in one step. The steam chest is constructed and mounted inthe same manner as previously described, but in addition to the stationary fluid discharging devices 20 intermediate stationary blades 37 are provided which are located between rows of reversing blades 21 on the rotors. As shown, each rotor has two rows of blades mounted in any suitable manner, but the number can begreater if desired. If the number is increased additional rows of stationary blades must be provided. With this arrangement the velocity of the fluid leaving the devices 20 is extracted by successive operations, commonly called velocity compounding, and hence the rotative speed of blade carrying element for a given steam velocity will be less than with the arrangement shown in Fig. 1.

In Fig. 3 is shown a furthermodificatwn where each rotor has a single row of reversing blades 21, but the steam, instead of flowing in multiple paths from the source to the condenser, flows serially through sald In this manner the energy of the steam is extracted by pressure steps or stages, and hence the pressure drop across each device 20 is less. This requires a slight change in the construction of the steam chest.

fore. In addition it has an annular dividing wall 38 through which the supply conduit 19 extends. This means that the chest has a high pressure chamber 18 delivering steam to the'right-hand discharging devices 20 and an intermediate pressure chamber 39 delivering steam to the left-hand discharging devices 20, the path of the steam being indicated by the arrows.

In Fig. 4 is a further modification wherein the steam chestjs divided into two parts by an annular perpendicular partition 40 with a supply conduit 41 leading to each of the chambers. This arrangement permits of admitting steam for reversing purposes to one orboth of the rotors as desired. In each conduit is a combined throttle and shut-off valve 42.

It will be seen by mounting the reversing blades outside of all the other blades that they occupy a favorable position, both from a mechanical and from a thermo-dynamic standpoint. The structure is simple, ac-

cessible, and sufficiently strong to withstand the stresses to which it is subjected. By locating the steam chest in the manner described, one structure serves bothas a steam chest and as a deflector. In this manner the total number of parts is reduced. Furthermore its location is such that it may be easily supported; the supply of steam may be readily admitted thereto, and as said structure also carries the stationary fluid directing devices for both the forward driving and reversing blades, it results in a mechanical simplification of the turbine as a whole. The most importantfeatures of the reversing arrangements reside in the fact that it does not interfere with the arrangement of the forward driving blade system and cooperating parts, it does not increase the overall length of the turbine, it adds only very slightly to the diameter, and the steam passages are short and very direct.

In accordance with the provisions of the patent statutes, I have described the princi- It is provided with the deflector walls 13 and 14 and annular wall 17 as 'be-' means.

What .I claim as new and desire to secure by LettersPatent of the United States, is,-

1. In an elastic fluid turbine the combination of a rotor having an inner radial flow blade system and two outer concentric axial flow blade systems, said radial flow blade system and one of said outer axial flow blade systems being connected in parallel as regards the flow of elastic fluid for driving the rotor in a forward direction, and the other of said axial flow blade'systems being for driving the rotor in a reverse direction. 2. In an elastic fluid turbine, the combination of a rotor having an inner radial flow blade system, an outer axial flow blade system, both of said systems driving therotor in the forward direction, a second axial flow blade system surrounding the first for driving the rotor in the reverse direction, a casing means, and inlet and exhaust conduits.

3. In an elastic'fiuid turbine, the combinationof rotors having concentric rows of axially disposed blades through which the motive fluid flows radially to drive them in opposite directions, radially disposed blades mounted on the peripheries of said rotors and through which the motive fluid flows axially to drive the rotors in the reverse direction, an inclosing casing, and inlet and exhaust conduits.

4. In an elastic fluid turbine, the combination of two rotors, a radial flow system of blading mounted on each rotor, an axial flow system of blading for each rotor arranged-outside of said radial system, said systems cooperating to drive the rotors, a' second axial flow blading system arranged outside the first for driving the rotors in the reverse direction, an inclosing casing, and inlet and exhaust conduits.

5. In an elastic fluid turbine, the combination of two rotors, a casing therefor, concentric rings of blades arranged to drive the rotors in opposite directions for forward running, an outer axial flow blade system associated with each rotor to assist the radial flow blades, and an axial flow blade sysits direction of rotation.

6. In an elastic fluid turbine, the combination of two rotors, a radial flow blade system, parts of which are carried by both r'o tem associated with each rotor for reversing I tween the two axial flow blade systems, a

' nation of two rotors, a radial flow bladecasing inclosingthe rotors, and inlet and exhaust conduits. 7 In an elastic fluid turbine, the combination of two rotors, a radial flow blade system, parts of which are carried by both rotors for forward operation, two axial flow blade systems surrounding the first system, one for each rotor, for reverse operation, a fluid supply chest located between the two axial flow blade systems, a casing which incloses the rotors and chest, inlet conduits communicating with the radial flow blade system and the chest, and an exhaust conduit that is common to all of the blade systems. y

8. 'In an elastic fluid turbine, the combisystem, parts of which are carried by both rotors for forward operation, two axial flow blade systems surrounding the first system, one for each rotor, for reverse operation, a fluid supply'chest located between the two axial flow blade systems, a casing which inclosesthe rotors and chest, yielding means for supporting the chest from the casing to reduce the eflects of temperature changes,

and inlet and exhaust conduits.

9. In an elastic fluid, turbine, the combination of two rotors, a radial flow blade.

' system, the parts of which are carried by both rotors, an axial flow blade system, parts of which are earned by both rotors, a second axial flow blade system for reversing, parts of which are carried b both r0 tors, an annular deflector which irects motive fluid fromthe radial to the first mentioned axial flow system, stationary blades carried b the deflector, a supply chest that is partial y formed by'the deflector, stationary blades carried by the chest, said deflector and chest being located between the axial flow blades in the rotors, an inclosin'g casing, and inlet and outlet conduits.

10. In an elastic fluid turbine, the combination of a pair of rotors bladed for radial 11. In an elastic fluid turbine, the coinbi-' nation of rotor members bladed for radial flow of the fluid, two outer axial'flow blade systems,'one for each rotor, and a fluid distributing means arranged between the axial flow blade systems and containing. two chambers which are connected through one of the axial flow blade systems.

12. In anelastic fluid turbine, the combination of a pair of rotors havingcooperating concentric rows of blades through which the fluid flows radially to drive the rotors in opposite directions, two outer axial flow blade systems associated one with each rotor for reversing, an annular fluid distributer.

arranged between said axial flow blade system and provided with an inner and an outer fluid chamber which communicate with each other through one of the axial blade systems, a supply conduit communicating duit which receives fluid from the other axial blade system.

13.. In an elastic fluid turbine, the combi-' nation of two rotors arranged face to face with concentricrows of axially extending blades carried by the rotors and through which the motive fluid flows radially to drive the rotors. in opposite directions, reversing blades located outside of said radial flow blades on both rotors for reversing their direction of rotation, means surrounding the radial flow blades, for supplying fluid to the reversing blades, inclosing casing means for the rotors, and inlet and exhaust 'conduits. 1 I

In witness whereof I have set my hand this 18th day of September, 1917.

FREDRIK LJUNGs'rRoM.

- with the inner chamber, and an exhaust con- 

